1x23 "The One with the Birth"

Carol goes into labor, prompting Monica to begin thinking about having a baby of her own. When Ross and Susan cannot stop bickering over who gets to help Carol more, Phoebe drags both of them into a closet to settle their differences – but all three end up getting locked in just as Carol is about to give birth to the baby. Rachel flirts with an OB/GYN who has a love-hate relationship with women's private parts due to seeing them every day at work. Joey ends up assisting birth for a single mother (played by Leah Remini).